1. Field of the Invention
The present invention relates in general to electronic appliances and in particular to circuits, systems and methods for information privatization in personal electronic appliances.
2. Description of the Related Art
Handheld personal electronic appliances have become increasingly popular as new technologies have allowed for the production of affordable devices with a high degree of functionality. One such device is the portable digital audio player, which downloads digital audio data, stores those data in a read-writeable memory, and converts those data into audio on user demand. The digital data is downloaded from a network or retrieved from a fixed medium, such as a compact disk, in one of several forms, including the MPEG Layer 3, ACC, and MS Audio protocols. An audio decoder, supported by appropriate firmware, retrieves the encoded data from memory, applies the corresponding decoding algorithm and coverts the decoded data into analog form for driving a headset or other portable speaker system.
In order to prevent the unauthorized download of copyrighted material, such as music segments, some means of controlling the operation of a the personal appliance is desirable. This could be implemented for example through the issuance of passwords or software kernels authorizing download the relevant information. The passwords or software must be secured to prevent end user copying, distribution and tampering. Moreover, the audio decoder may be operating from proprietary firmware which must also be protected against copying or tampering.
In sum, what are needed are methods, circuits and systems for securing information in personal digital appliances. To this end, the ability to secure this information should not depend on where in the appliance it is stored, whether it be in memory internal or external to the primary processing chip. Moreover, implementation of security should not waste resources, such as the available memory space, which could be used more directly for processing operations. Additionally, the security methods and hardware should be applicable to a wide range of different system configurations.
According to the principles of the present invention, a system is disclosed which includes a central processing unit operating in response to a set of instructions for processing information. An interface is included which provides access to selected circuitry forming a part of the system by an external device. A set of non-volatile programmable security elements selectively enable and disable the operation of the interface to provide a private environment for processing the information. The principles of the present invention provide, among other things the ability to privatize information in personal digital appliances. These principles can be implemented in a manner which does not waste processing resources, such as available memory space, which could be more directly used for processing operations. Moreover, these principles can be applied to a wide range of different system configurations that do not depend on where in the appliance the private information is to be stored, whether it be in memory internal or external to the primary processing chip.